Abstract: Heat transfer sound has been an unavoidable problem in the development of air conditioning, and the current common practice is to set up a simple expansion muffler in the pipeline of the outer unit to control it. However, due to the physical limitations of simple expansion muffler, it is impossible to achieve the effective unification of high noise reduction and small volume. In order to solve this contradiction, the finite element method was firstly applied to analyze the influence of relevant parameters on the muffling performance of partial perforated straight-through pipe mufflers, and it was found that the perforated section length, location and perforation rate had a significant influence on the muffling performance. These laws were then applied to optimize an air-conditioning muffler, achieving a 43.9% reduction in the volume of the muffler material without weakening or exceeding the original muffler's silencing performance. Finally, the heat transfer sound test of the whole machine shows that the optimized partial perforated straight-through pipe muffler is comparable to the original muffler in quiet wind gear, with an advantage in the low wind gear.

Key words: Partial perforated, Muffler, Transmission loss